In particular in the context of an aeroengine of standard type, it is known that lowering the temperature of the primary air flowing through the compression stages of the engine makes it possible, for given compressor technology, either to reduce the fuel consumption of the engine, or else to reduce its emission of pollution such as nitrogen oxides (NOx). If it is desired to maintain the initial temperature, it is then possible to increase the overall pressure ratio (OPR), thus making it possible to reduce fuel consumption, otherwise if it is desired to maintain the OPR, then the temperature reduction reserves to reduce the emission of NOx pollution.
Attempts have already been made to reduce the temperature of the primary air by using a heat exchanger. For example, this is described in EP 1 555 406 or U.S. Pat. No. 4,254,618. In those two examples, a fraction of the primary air is taken upstream from the high-pressure compressor and caused to pass through a heat exchanger mounted in the secondary air stream, and the air that has been cooled is returned to the inlet of the high-pressure compressor. However, that disposition does not make it possible to obtain a genuinely satisfactory reduction in temperature.
Document FR 2 482 196 describes heat exchanger means in accordance with the precharacterizing portion of claim 1.